Recent advances in low-power technologies have resulted in the proliferation of inexpensive handheld mobile computing devices. Soon, just like the Internet empow- ered a whole new world of applications for personal computers, the development and deployment of robust ubiquitous wireless networks will enable many new and exciting futuristic applications. Certain to be an important part of this future is a class of networks known as "mobile ad hoc networks." Mobile ad hoc networks (or simply "ad hoc networks") are local-area networks formed "on the spot" between collocated wireless devices. These devices self-organize by sharing information with their neigh- bors to establish communication pathways whenever and wherever they are. For ad hoc networks to succeed, however, new protocols must be developed that are capable of adapting to their dynamic nature. In this dissertation, we present a number of adaptive protocols that are designed for this purpose. We investigate new link layer mechanisms that dynamically monitor and adapt to changes in link quality, including a protocol that uses common control messages to form a tight feedback control loop for adaptation of the link data rate to best match the channel conditions perceived by the receiver. We also investigate routing protocols that adapt route selection according to network characteristics. In particular, we present two on-demand routing protocols that are designed to take advantage of the presence of multirate links. We then investigate the performance of TCP, showing how communication outages caused by link failures and routing delays can be very detrimental to its performance. In response, we present a solution to this problem that uses explicit feedback messages from the link layer about link failures to adapt TCP's behavior. Finally, we show how link failures in heterogeneous networks containing links with widely varying bandwidth and delay can cause repeated "modal" changes in capacity that TCP is slow to detect. We then present a modifed version of TCP that is capable of more rapidly detecting and adapting to these changes.

We investigate the issues in making a delay-based protocol adaptive to heterogeneous environments. We assess and address the problems a delay-based protocol faces when competing with a loss-based protocol such as TCP. We investigate if noise and variability in delay measurements in environments such as cable and ADSL access networks impact the delay-based protocol behavior significantly. We investigate these issues in the context of incremental deployment of a new delay-based protocol, PERT. We propose design modifications to PERT to compete with the TCP flavor SACK. We show through simulations and real network experiments that, with the proposed changes, PERT experiences lower drop rates than SACK and leads to lower overall drop rates with different mixes of PERT and SACK protocols. Delay-based protocols, being less aggressive, have problems in fully utilizing a highspeed link while operating alone. We show that a single PERT flow can fully utilize a high-speed, high-delay link. We performed several experiments with diverse parameters and simulated numerous scenarios using ns-2. The results from simulations indicate that PERT can adapt to heterogeneous networks and can operate well in an environment of heterogeneous protocols and other miscellaneous scenarios like wireless networks (in the presence of channel errors). We also show that proposed changes retain the desirable properties of PERT such as low loss rates and fairness when operating alone. To see how the protocol performs with the real-world traffic, the protocol has also been implemented in the Linux kernel and tested through experiments on live networks, by measuring the throughput and losses between nodes in our lab at TAMU and different machines at diverse location across the globe on the planet-lab. The results from simulations indicate that PERT can compete with TCP in diverse environments and provides benefits as it is incrementally deployed. Results from real-network experiments strengthen this claim as PERT shows similar behavior with the real-world traffic.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: Loss; TFRC; AIMD; TCP. Includes bibliographical references (p. 147-155).

Ever had an experience of forgetting to do something very important on a place you just past?. Remembering, on arrival at your destination afterward, requires an action to return to the task location. This can be unproductive and perhaps result to frustration. The purpose of this thesis is to develop a “Location Task-To-Do manager” an android mobile application that will efficiently organizes task-to-do list and remind an individual to perform a task at a pre-defined location through notification and alert messages. The methods used includes,  investigation of pre-existing systems, requirement elicitation survey technique, three-tier architecture design pattern, iterative development life-cycle model, acceptance test plan and a sets of other technology such as  Java SDK, Android APIs, TCP/IP protocol, object oriented programing techniques and MySql relational database. The result showed that, installed “Location Task-To-Do manager” application on individual mobile devices/smartphones were capable of creating task, adding task, editing task, deleting task, sharing task and setting task location through its user friendly graphical interfaces. Users are able to receive notification to perform a task within a minimum distance of 1km to the exact task location.

Thesis (Ph.D.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references (ℓ. 98-99)

Thesis (M.App.Sc.) - Carleton University, 2003. / Includes bibliographical references (p. 90-92). Also available in electronic format on the Internet.

Chemnitz, Techn. Univ., Diplomarb., 2005.

Universiẗat, Diss., 2006--Bochum.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisors: Brian L. Evans and Gustavo de Veciana. Vita. Includes bibliographical references.

Zugl.: Stuttgart, Universiẗat, Diss., 2004.